scholarly journals Spontaneous Development of Left Ventricular Hypertrophy and Diastolic Dysfunction in Mice Lacking All Nitric Oxide Synthases

2010 ◽  
Vol 74 (12) ◽  
pp. 2681-2692 ◽  
Author(s):  
Kiyoko Shibata ◽  
Yasuko Yatera ◽  
Yumi Furuno ◽  
Ken Sabanai ◽  
Naoya Morisada ◽  
...  
Circulation ◽  
2014 ◽  
Vol 130 (suppl_2) ◽  
Author(s):  
Pamela D Winterberg ◽  
Rong Jiang ◽  
Bo Wang ◽  
Sonal Harbaran ◽  
Mary B Wagner

Introduction: The underlying mechanisms contributing to uremic cardiomyopathy during chronic kidney disease (CKD) are poorly understood, limiting treatment options. Hypothesis: We aimed to determine if altered calcium (Ca2+) handling in cardiomyocytes contributes to diastolic dysfunction in a mouse model of CKD. Methods: CKD was induced in male 129X1/SvJ mice through five-sixths nephrectomy in a two-stage surgery. Age-matched mice served as controls. Transthoracic echocardiography and speckle-tracking based strain analysis (Vevo2100, VisualSonics, Toronto, Canada) were performed at 8 weeks post-CKD (n=7-8) to assess heart structure and function. Cardiomyocytes isolated from mice with or without CKD (n=3 mice per group, 10-12 cells/mouse) were loaded with Fura 2-AM, paced by field stimulation (1 Hz), and imaged with a dual-excitation fluorescence photomultiplier system (IonOptix Inc, Milton, MA) to measure Ca2+ transients and sarcomere length. Sarcoplasmic reticulum Ca2+ content was determined following rapid application of caffeine.[[Unable to Display Character: &#8232;]] Results: CKD mice displayed left ventricular hypertrophy (LVAW;d 1.46 ± 0.134 vs 1.04 ± 0.129 mm; p<0.001) and decreased longitudinal strain (19 ± 4.1% vs 30 ± 2.3%; p<0.0001) compared to control mice. Resting sarcomere length was significantly shorter in cardiomyocytes isolated from CKD mice compared to normal mice (1.86 ± 0.054 vs 1.89 ± 0.047 nm; p = 0.016), but relaxation time was unchanged (0.21 ± 0.12 vs 0.21 ± 0.15 seconds, p=0.4). Unexpectedly, the baseline cytosolic Ca2+ content was lower in uremic myocytes (1.22 ± 0.353 vs 1.46 ± 0.252 AU, p=0.002). However, the Ca2+ transient amplitude (0.39 ± 0.177 vs 0.41 ± 0.167 AU, p=0.4) and sarcoplasmic reticulum Ca2+ content (1.15 ± 0.321 vs 1.24 ± 0.550 AU, p=0.4) were comparable between CKD and normal cardiomyocytes.[[Unable to Display Character: &#8232;]] Conclusions: Mice with CKD have signs of left ventricular hypertrophy and diastolic dysfunction on echocardiography. Cardiomyocytes isolated from mice with CKD have shorter diastolic sarcomere length implying impaired relaxation, yet paradoxically have decreased diastolic calcium. Thus Ca2+ accumulation during diastole does not appear to contribute to impaired relaxation in this model.


2005 ◽  
Vol 64 (1) ◽  
Author(s):  
Maria Teresa Manes ◽  
Manlio Gagliardi ◽  
Gianfranco Misuraca ◽  
Stefania Rossi ◽  
Mario Chiatto

The aim of this study was to estimate the impact and prevalence of left ventricular geometric alterations and systolic and diastolic dysfunction in hemodialysis patients, as well as the relationship with cardiac troponin as a marker of myocardial damage. Methods: 31 patients (pts), 19 males and 12 females, age 58.1±16.4 (26 on hemodialysis, 5 on peritoneal dialysis) and 31 healthy normal controls were enrolled. Echocardiography measurements were carried out according to the American Society of Echocardiography recommendations. Left ventricular mass was calculated, according to the Devereux formula and indexed to height and weight 2.7. Doppler echocardiography was performed to study diastolic function by measurements of isovolumetric relaxation period (IVRT), E wave deceleretion time (DTE) and E/A ratio. Cardiac troponin was measured by a third generation electrochemiluminescence immunoassay. Statistical analysis was performed using the t-test for between-group comparisons and the Pearson and Spearman’s tests to investigate correlations; p values of &lt;0.05 were considered statistically significant. Results: Eccentric hypertrophy was the most frequent pattern (n=17; 55%), followed by normal cardiac geometry (n=7; 23%), and concentric hypertrophy (n=5; 16%). Only 6% of pts (n=2) showed concentric remodelling. Systolic dysfunction was present in terms of endocardial parameters in 3 pts (9%) (fractional shartening &lt;25%, EF&lt;50%), but in terms of midwall myocardial shortening in 51% (n=16). Diastolic dysfunction was present in 87% (n=27) with a pattern of impaired relaxation (in 5 without left ventricular hypertrophy). E/A was negatively correlated with age (r=-0.41, p=0.02); DTE was positively correlated with posterior wall thickness (r=0.36, p=0.05) and interventricular septum thickness (r=0.45, p=0.01); cardiac troponin was positively correlated with age (r=0.50, p=0.00), left ventricular mass (r=0.41, p=0.02), posterior wall thickness (r=0.41; p=0.02) and interventricular septum thickness (r=0.39, p=0.03) but not with diastolic dysfunction parameters. No significant difference was found in terms of duration of dialysis between patients with normal left ventricular geometry and those with left ventricular hypertrophy, but a significant difference in age was found (p=0.03). Pts with diastolic dysfunction had more frequent hypotensive episodes during dialysis (p &lt;0.01). Conclusion: Impaired geometry and cardiac function is frequently observed in pts undergoing hemodialysis. Diastolic dysfuction is associated to a geometric pattern of left ventricular hypetrophy, although it can be an isolated initial manifestation of myocardial damage. Depressed midwall myocardial shortening can discriminate left ventricular dysfunction better than traditional endocardial systolic indexes.


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